Plastic materials have several characteristics that make them advantageous for use in a wide variety of applications. For example, many plastic materials are relatively inert, and can thus be used to store a variety of materials, including foodstuffs. Plastics also have a relatively high strength to weight ratio, can be made opaque or transparent, and can be made water and/or air tight. Because of these characteristics, plastics are used in almost every aspect of modern life.
One such use of plastics is as storage containers, and especially food storage bags. Because plastic is inert, plastic food storage bags can be used to store acidic foods, such as those containing tomato sauces, vinegars, and the like, for extended periods of time without concern that the bag will break down. The food storage bags can also be made essentially transparent, thereby permitting a user to easily see what is stored inside the bag. The high strength to weight ratio also means that the bag can store relatively heavy foods, such as meats, dense vegetables, and the like, without fear of the bag breaking while the bag and its contents are being moved. In addition, given the waterproof nature of such plastic bags, they are ideal for containing both solids and liquids.
One problem with plastic food storage bags is that they trap air inside the bag with the food. Such air provides oxygen, water, and other chemicals needed by bacteria and other microorganisms to facilitate breaking down (i.e. spoiling) of the bag's contents. The air also allows ice crystals to form on the food when the bag is placed in a freezer. Such ice crystals can cause “freezer burn”, which is undesirable for consumers.
Some in the prior art, such as the Food Saver line of plastic food storage bags and related equipment distributed by Jarden Corporation of Rye, N.Y., have addressed this by creating a bag whose open end is placed into a specialized apparatus. The apparatus draws the air from the bag though the open end, and then electronically welds the plastic bag closed. Although such a system is advantageous, the bags are essentially one-time-use products, are sometimes awkward to handle, and cannot be resealed.